Answer:
Kp = 7.4727
Explanation:
Let's write the balanced equilibrium reaction:
2NH₃ <-------> N₂ + 3H₂   Kp = ??
Now, if we want to calculate the Kp, we need to write an ICE chart with this reaction, which is the following:
     2NH₃ <-------> Nâ‚‚ + 3Hâ‚‚ Â
I. Â Â Â Â 4,5 Â Â Â Â Â Â Â Â 0 Â Â Â Â 0
C.    -2x         +x   +3x
E.     4,5-2x       x    3x
According to this chart, the Kp expression should be:
Kp = (PH₂)³ * (PN₂) / (PNH₃)²  (1)
The value of x, we already know it because the problem states that the amount of nitrogen gas is 1.1 atm, so replacing this value into (1) we have:
Kp = (3*1.1)³ * (1.1) / (4.5 - (2 * 1.1))²
Kp = 39.5307 / 5.29
Hope this helps